Fully photonic wireless broadband base station

ABSTRACT

The invention relates to base stations in communication networks. In more particular the invention relates to cellular base stations such as 3G/4G and WLAN base stations. Some or all of the aforementioned advantages of the invention are accrued with a fully photonic base station ( 200 ) that powers itself with solar photons, provides radio network access and relays an optical photonic beam ( 220, 221, 230, 231 ) through air encoded with the data from radio signals of computer users and mobile phone users to the Internet and the global telecommunication network. A system engineer can build a network with the inventive base stations in a matter of days. He simply walks to the roof of houses and points the optical beams to other base stations in adjacent houses.

TECHNICAL FIELD OF INVENTION

The invention relates to base stations in communication networks. Inmore particular the invention relates to cellular base stations such as3G/4G and WLAN base stations.

BACKGROUND

The famous last mile problem has been the greatest unsolved problem intelecommunication since the days of Thomas Alva Edison and AlexanderBell. This problem, of course, reads as follows: more than 90% of allpeople are within a mile from an access point to the globaltelecommunication network. However, more than 99% of the cost is spentaccessing that last mile, i.e. digging up roads and laying wires andoptical fibres to households and base stations to transfer data anddeliver power to them.

Even further, when one operator has put up the capital to reach thatlast mile to the customer, it becomes practically impossible for newcompeting operators to start competing by building another accesssolution to the customer. The original operator can always price itsservice temporarily so, that it is uneconomical to the competingoperator to incur the capital outlay cost of a competing last mileconnection in a situation that might lead to price competition, butstill the capital outlay cost that the original operator invested isproducing a hefty return on investment. Needless to say, severalcompetition laws and government watchdogs have been implemented to steerthis monopolistic market dynamic to more free competition.

In the prior art it is known that solar cells have been used to powerlight houses, for example on the Baltic Sea.

In the prior art it is also known that free space optics connections canbe used to replace optical fibre connections, by shooting a laser beamfrom one building to another.

In the prior art it is also known that free space optics connectionshave been realised in space from scientific satellites that have beenpowered by solar panels.

WO2006/044519 discusses radio-to-fibre conversion and mentions solarcell powered picocells.

The prior art techniques are incapable of solving the last mile problem.

SUMMARY

The invention under study is directed towards a system and a method foreffectively creating a base station that is completely void of externalwire connections, thereby solving the last mile problem.

A further object of the invention is to present a 3G/4G/LTE/WLAN (3^(rd)Generation, 4^(th) Generation, Long Term Evolution, Wireless Local AreaNetwork) communication network that can be built at a fraction of thecost of conventional communication networks.

An even further object of the invention is to better enabletelecommunications operators new to a particular market to startcompeting with existing original operators, thereby driving down cost inthat market.

One aspect of the invention involves a fully photonic cellular basestation that can be placed e.g. on the roof of a building, and madefully operational in 10 minutes without any infrastructure improvingwork. The inventive base station is powered by one or more solar cells,and therefore does not need a grid electricity connection. The solarcells typically charge a battery and/or have at least one low band gapphotodiode layer, so that excess power during intense sunlight is storedin the battery to power the base station at night and times of cloudyweather. The low band gap material is designed to produce someelectricity even in cloudy weather when no high energy photons arepresent in sufficient quantity. One such low band gap material is InSb,with a band gap of 0.17 eV (electrovolts). The base station further hasa laser communication link that transmits an optical beam through theair to avoid the need of installing optical fibres or othercommunication wires. The laser light is typically generated by asemiconductor photodiode. One of the laser transmitters is typically aquantum cascade laser that transmits very low energy photons, which arenot as easily scattered by advection fog. The inventor received theEuropean patent EP 1 476 968 B1 for the weather resilient FSO (freespace optics) link, and this publication is cited here as reference. Anylaser transceiver described therein can be used to realise the opticallink of the inventive base station in this application. In one aspect ofthe invention the optical communication link is not realised with alaser, but instead with a conventional photodiode, such as a LED (LightEmitting Diode).

The laser link transmitter is typically pointed to an optical receiver,so that a line of sight connection is formed. The base station furtherhas radio transceivers such as WCDMA (Wideband Code Division MultipleAccess)/3G/4G/LTE transceivers or WLAN (Wireless Local Area Network)transceivers. The subscriber terminals of users such as consumers andbusinesses access the network of the base station by communicating onthe frequencies of the said transceivers.

A competing telecommunication operator will first put an opticaltransceiver e.g. on the roof of a building that hosts its exchange,central office (CO) and/or access point to a core optical network. Thecompeting operator service person will then take the base station of theinvention, and transport it to a nearby roof of another building with aline of sight connection to the optical transceiver at the core opticalnetwork access point. The base station will be positioned and/or focusedso that the optical laser communication link is formed between the basestation and the optical transceiver at the core optical network. Thebase station will then connect to subscriber terminal by providing radionetwork coverage in its proximity Phone, Mobile phone, computer,television, radio and/or laptop computer users will simply form a radioand/or microwave connection to the base station, which will send dataonwards to and from the subscriber terminals with the optical laserlink, connecting said subscriber terminals to the internationaltelecommunication network and/or Internet, with first theradio/microwave connection to the base station and then the free spaceoptical connection to the optical core network.

Also in a preferred aspect of the invention the base station has aplurality of optical laser links, forming a network with other opticaltransceivers. This type of a mesh network configuration allows signalsto reroute if the line of sight connection is lost for some reasonbetween two base stations. However, the light beam is typicallyexpanded, for example with a telescope, to a diameter that issufficiently large that a bird cannot block the entire beam.

Some or all of the aforementioned advantages of the invention areaccrued with a fully photonic base station that powers itself with solarphotons, provides radio network access to subscriber terminals and sendsa photonic beam encoded with the data from radio signals of subscriberterminals, such as computer users and mobile phone users, to theInternet and/or the global and/or local telecommunication network. Asystem engineer can build a network with the inventive base stations toa city like Helsinki (1 million inhabitants) in a matter of days. Hesimply walks to the roofs of houses and points the optical beams toother base stations in adjacent houses. A visit to a roof will takeroughly 10 minutes.

A transceiver base station in accordance with the invention providingaccess to a radio and/or microwave communication network via at leastone radio transceiver is characterised in that,

-   -   said base station comprises an optical data communication link        arranged to transmit photons through free space,    -   said base station comprises at least one solar cell.

A transceiver base station in accordance with the invention is arrangedto provide radio and/or microwave communication network access to atleast one subscriber terminal via at least one radio and/or microwavetransceiver and characterised in that,

-   -   said base station comprises at least one laser and/or photodiode        data communication link arranged to transmit and/or receive        photons through free space,    -   said base station comprises at least one solar cell.

A base station in accordance with the invention is arranged to provideradio and/or microwave communication network access to at least onesubscriber terminal via at least one radio and/or microwave transmitterand/or receiver and is characterised in that,

-   -   said base station comprises at least one laser and/or photodiode        data communication transmitter and/or receiver arranged to        transmit and/or receive photons through free space,    -   said base station comprises at least one solar cell.

A method of providing communication network access in accordance withthe invention by operating a network of radio and/or microwave basestations offering communication network access to a plurality ofsubscriber terminals via a radio and/or microwave connection, comprisingthe following steps:

-   -   powering said base stations with at least one solar cell in the        same locations as the said base stations,    -   connecting said base station to a communication network with an        optical data communication link through free space.

A method of providing communication network access in accordance withthe invention by operating at least one base station offeringcommunication network access to a plurality of subscriber terminals viaa radio and/or microwave connection comprises the following steps:

-   -   powering said at least one base station with at least one solar        cell in the same location as the base station,    -   connecting said base station to a communication network with at        least one laser and/or photodiode data communication link        through free space.

“Radio” and “microwave” are in this application construed as the part ofthe electromagnetic spectrum where the radiation source acts as anessentially non-directional (radiates to all directions) point radiator.

“Optical” is in this application construed as the part of theelectromagnetic spectrum which can be produced by photodiode emission.Thus “optical” is not limited to the visible spectrum in thisapplication, but can reach to 70,000 nm and beyond, which is the currenthighest wavelength that can be achieved by quantum cascade lasers. Also,the term optical is to comprise those laser wavelengths that providedirectional radiation with other lasing mediums, such as gas lasers.These wavelengths still relate to photons that require a line of sightconnection, i.e. are directional. The optical band is thus to beconstrued as 100 nm to 1 mm in this application, comprising the UV,visible and the infrared.

In one exemplary embodiment of the invention, the optical wavelengths ofthe base station are between 1-100 micron, and WLAN and GSM wavelengthsare 0.1-0.2 m. Roughly, this means that the optical connection canpackage the data of 1000-100000 WLAN and/or GSM connections, or othersimilar radio and/or microwave connections with its higher frequency.

“Data communication link” in this application is construed as data thatis electronically modulated to the signal, e.g. an optical signal.Hence, a person flashing a flashlight, or a lighthouse providing awarning light is not understood as a data communication link in thisapplication.

“Same location” in this application is construed as physically and/ormechanically attached to the same device, and/or connected with a wireat the same address. I.e. providing solar electricity with the powergrid from a distant solar panel would not be in the same location asconstrued in this application.

“Free space” is generally construed as air in this application, butcould also comprise water for underwater applications, and/or spaceand/or vacuum for space and/or laboratory applications. Hence, anoptical fibre or other waveguide such as copper cable is not construedas free space in this application. However, an optical fibre, mirror, orother waveguide can be used to lead the optical beam out of the basestation to free space in accordance with the invention. For example anapproximately 10 cm section of a waveguide leading out of the basestation is in accordance with the invention and handy and practical forpointing the beam that is arranged to traverse through free space to thereceiver. I.e. it is in accordance with the invention for the systemengineer to e.g. twist such a waveguide so that the optical beam pointsto the desired receiver with a clear line of sight.

In a preferred embodiment the base station is quite small, typically thesize of the current WLAN base stations, i.e. 0.1-2 kg. In one preferredembodiment the inventive base station provides a “plug and play”functionality, i.e. it becomes automatically operational as soon as itis turned on. To provide this functionality, the base station may bearranged to automatically provide and/or acquire at least one networkaddress, e.g. at least one IP address, and/or the like networkconfiguration data to/from at least one subscriber terminal, at leastone another base station, and/or at least one router or other device inthe optical network.

In one aspect of the invention, the radio/microwave cell size is quitesmall 10-50 m, and the backhaul free space optical link is reasonablylong 50-1000 m. This is especially preferable because it allows for avery low power base station, as transmission powers can be controlledwithin the limits of the power provided by the solar cells, even thoughthe solar cells are quite small in area.

The invention quite clearly offers great synergistic advantages that gobeyond the sum of its parts. Using a FSO (free space optics) solutionindividually relieves the network operator from the need to buildoptical cables to the base station, but wire infrastructure would stillneed to be built, i.e. power cords. Similarly using the solar cell for anetwork base station relieves the operator from making sure gridelectricity is available, but again an optical fibre would need to bebuilt. The invention allows the system engineer merely to only requestauthorisation from the tenants to place the base station on the roof.There is no need to consult the tenants for permissions to conductinfrastructural changes to the building itself, such as providing apower cord to the roof, or allowing for optical fibre wiring. Theinventor has calculated that this saving should exceed more than 5000Euros/building, which is the standard quoted rate that largetelecommunications companies cite as the cost of connecting a centralHelsinki building to optical broadband, when fibre is available.

In one embodiment the base station is realised as a personal orhousehold level version. The user just puts the base station on hiswindow sill or roof, and points its free space optical link to anoptical transceiver and/or base station nearby and realises wirelessbroadband at his household or office.

Furthermore, the inventive base station is very cheap to manufacture inlarge quantities. Therefore it has the added advantage that the cellsize served by the base station can be made very small. This allows forthe introduction of quite small very broadband, high bandwidth, radiocells. These small very high bandwidth radio cells have the advantagethat they can be used to substitute an optical fibre connection to aresidential or office unit. In some embodiments the range of the basestation is about 10-100 m to cover one residence. In one embodiment therange is about 500 m, which is arranged as sufficient to reach from theroof of a skyscraper to street level.

In addition and with reference to the aforementioned advantage accruingembodiments, the best mode of the invention is considered to be a fullyphotonic base station that provides radio/microwave network access suchas WLAN-, LTE-, 3G-/4G-access to mobile phones and computers.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail withreference to exemplary embodiments in accordance with the accompanyingdrawings, in which

FIG. 1 demonstrates an embodiment of the method of operating theinventive base station as a flow diagram.

FIG. 2 demonstrates an embodiment 20 of the base station in accordancewith the invention as a block diagram.

FIG. 3 demonstrates an embodiment 30 of the network of base stations inaccordance with the invention as a block diagram.

Some of the embodiments are described in the dependent claims.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows the operation of an embodiment 10 of the inventive methodas a flow diagram. In phase 100 at least one radio transceiver of a basestation maintains a communication connection to at least one subscriberterminal. The subscriber terminal is typically a mobile phone and/or acomputer that is connected to the base station transceiver with its ownradio transceiver. The connection between the transceivers is typicallya wireless data connection such as a WLAN-, GPRS-, 3G-, 4G- and/orWCDMA, but can also be a circuit switched telephony connection, such asGSM, CDMA or the like mobile telephony connection. In some embodimentsthe connection between the base station and the subscriber terminal canalso be a proprietary communication connection, packet based- and/orcircuit switched connection in accordance with the invention. Forexample military applications and temporary data connections used foremergency services or big sports or entertainment events at temporarylocations are also in accordance with the invention.

The subscriber terminal is typically a phone, a mobile phone, a PDA(personal digital assistant), a laptop computer, a television, a videoset, a radio and/or computer. In some embodiments the subscriberterminal may use any operating system such as MacOS, Microsoft Windowsand/or Linux or the like.

Typically one base station provides communication access to severalsubscriber terminals that are within range of the radio and/or microwavetransceiver. In phase 110 at least two communication connections from atleast two subscriber terminals are received and relayed onwards using afree space optical link (FSO). For example the phone conversations ofthree people with three different subscriber terminals each can bepacked into the same free space optical connection as an Internetconnection from a computer accessing the base station using e.g. theWLAN protocol or any other wireless data communication protocol.

The free space optical link is typically realised with a lasertransceiver that abides to an existing optical networking protocol, suchas SONET and/or SDH to name a couple of examples. In some embodimentsthe base station has a WLAN<->SONET adapter, or a similarradio/microwave communication signal<->optical communication signaladapter, such as a WCDMA<->SONET, or the like adapter.

In phase 120 at least one solar cell is at the same location and powerssaid base station. The solar cell is typically a photovoltaic solarcell, and the base station is preferably outdoors to maximise incomingsolar energy. However, the invention can be used with the base stationand the solar cell indoors also. In some embodiments the solar cell isdesigned to produce electricity from photons emitted by indoor lightingvery efficiently. This is typically done so that the band gap of thesolar cell is adjusted to or close to the peak of the intensity in theindoor lights.

The solar powered base station thus relays typically non-visible opticalrays to other base stations and optical transceivers connected to thecore optical network. There is typically no power cord, or no opticalfibre, or other communication or power wires going into the basestation. The base station is simply a box that needs to be placed sothat:

-   -   a) the surface with the solar cell receives solar light        radiation,    -   b) there is a line of sight connection to another base station        and/or optical transceiver.

Consequently, all the hard work needed in setting up base stations canbe replaced by mere clever positioning of the base station in accordancewith the invention.

It should be noted that any features, phases or parts of the method 10can be freely permuted and combined with embodiments 20 and/or 30 inaccordance with the invention.

FIG. 2 shows an embodiment 20 of the inventive base station as a blockdiagram. The base station 200 typically has one or more antennas 210,211 for transmitting and/or receiving radio signals to and from at leastone subscriber terminal(s) 250, 251. The antennas can be any size inaccordance with the invention. However, the antennas are preferablyquite small to increase the portability of the truly wireless inventivebase station 200. For example for a GSM and/or WLAN base station theantennas could be in the centimetres size scale in some preferableembodiments, to correspond with the wavelengths of 0.167 m and 0.12 mrespectively.

Any data sent from the subscriber terminals to the base station overradio and/or microwave is formatted and modulated to a form that can beoptically sent onwards from the base station. The radio signals aremodulated into an optical signal that is sent with a FSO (free spaceoptics) link 220. The FSO link will typically be realised by laserphotodiodes that emit photons in the wavelength range from visible toabout 100,000 nm. In order to achieve a dynamic range from 1550 nm to70,000 nm one alternative is to use a normal SONET/SDH opticaltransceiver for the 1550 nm optical channel and have a longer wavelengthchannel as a backup for inclement weather, such as advection fog,utilising a quantum cascade laser (QCL), as explained in my patent EP 1476 968 B1. The inventor is currently aware that QCL lasers can reach to70,000 nm. In a preferred embodiment of the invention the QCL laser issimilarly modulated in accordance with the same optical communicationstandard as the shorter conventional photodiode laser, for example usingSONET and/or SDH. In one embodiment of the invention at least oneoptical communication link 220, 221 is not realised with a laser, butinstead with a conventional photodiode, such as a LED (Light EmittingDiode).

In some embodiments the base station 200 comprises several FSO links220, 221 that enable the base station 200 to send and receive opticalsignals to different directions. In some embodiments the base stationnot only joins the radio and/or microwave signals from the subscriberterminals in its own cell, i.e. within the range of its radiotransceivers, but it also joins optical signals received from one ormore other base stations and relays both the incoming radio and opticalsignals onwards. Quite clearly any incoming optical signal destined tothe subscriber terminals in the cell of the base station can also beformatted to a form suited for radio signaling and communicated to thesubscriber terminals in the cell of the base station.

Quite clearly it is in accordance with the invention to relay the radiosignals from the subscriber terminals optically to any network, such asthe Internet, telephony network, or any other data network, such as aproprietary and/or closed data network. Quite clearly both mobilewireless radio and wireless radio can be supported by the base stationsin accordance with the invention. The base stations can be programmed tosupport cell to cell mobility, i.e. dynamic handovers from cell to cellby network management software, as implemented with prior art cellularphone networks for example.

The base station 200 is powered by at least one solar cell 200. Thesolar cell is typically a tandem solar cell, which has a higherefficiency per unit area, so that the base station can be made as lightand to have as powerful photovoltaic solar cell as possible. In apreferred embodiment of the invention, the base station is quite flat,with the top surface housing the solar cell and facing the sky and theincident sunlight. The sides of the base station have the optical links220, 221. It is also possible in some embodiments to have at least oneexternally protruding waveguide or waveguides, typically an opticalwaveguide, lead out from the base station. This waveguide and/or thesewaveguides are used point at least one beam of an optical link 220, 221,and the said at least one waveguide and/or waveguides can be twistedand/or positioned so as to direct the optical beam in accordance withthe invention. This feature is advantageous in configuring the opticalbeams to provide network access fast on the roof of a building. Asexplained earlier, there can be many wavelengths in the optical link220, 221, for example 1550 nm from a standard SONET laser and 70,000 nmfrom a QCL laser. These wavelengths typically require differentwaveguides, and in one embodiment the waveguide is arranged so that ithas two co-axial waveguides in it, one for the shorter and one for thelonger wavelength. Naturally there can be any number of waveguides fordifferent wavelengths within one waveguide. It is in accordance with theinvention to realize a waveguide in and/or to the base station thathosts several waveguides for different wavelengths, for example in astacked or co-axial configuration. The at least one antenna is/arepreferably built into the base station 200.

The solar cell 240 can be made from any of the following materials: Si(Silicon), polycrystalline silicon, thin-film silicon, amorphoussilicon, Ge (Germanium), GaAs (Gallium Arsenide), GaAlAs (GalliumAluminum Arsenide), GaAlAs/GaAs, GaP (Gallium Phosphide), InGaAs (IndiumGallium Arsenic), InP (Indium phosphide), InGaAs/InP, GaAsP (GalliumArsenic Phosphide) GaAsP/GaP, CdS (Cadmium Sulphide), CIS (Copper IndiumDiselenide), CdTe (Cadmium Telluride), InGaP (Indium Gallium Phosphide)AlGaInP (Aluminium Gallium Indium Phosphide), InSb (Indium Antimonide),CIGS (Copper Indium/Gallium diselenide) and/or InGaN (Indium GalliumNitride) in accordance with the invention. Further, it is in accordancewith the invention to use any of the solar cells listed in EuropeanPatents EP2261996 and EP 2226852 and European applications EP08735694.5and EP08803499.6 of the inventor to power the base station 200 inaccordance with the invention.

In some embodiments the solar cell produces DC current, and an AC/DCadapter is provided in the base station 200 to convert the solar celloutput current to AC for use of one or more electronic components insaid base station 200.

At least one optical link 220, 221 is typically equipped with a beamexpander 230, 231. The beam expander is typically used to expand thebeam to a preferred size so that birds that get into the beam do notblock the signal and small motion due to wind, insects or the like donot cause a full misalignment of the beam from the transceiver to whichit is pointed to. In some embodiments the beam expander is a telescopewith lenses. It is in accordance with the invention that different beamexpansion designs and/or materials are used for photons of differentwavelengths in accordance with the invention to accommodate short andlong wavelengths.

In some embodiments the optical link 220, 221 may also feature acollimator device.

In some embodiments the pointing and the beam expansion of the opticallinks 230, 231, is adjustable, so that the system engineer can quicklyposition the base station so that it receives enough sunlight and hasthe optical links pointed to the correct other transceivers in thenetwork. In some embodiments the optical link 220, 221, may comprise aretroreflector, typically arranged to provide optical feedback forcorrectly pointing a transmitter beam to a receiver in free space. It isin accordance with the invention to provide a retroreflector and/or adetector of reflected optical radiation in the base station, and/or atone end, the other end, or both ends of the free space optical link.

As said earlier, one or more laser emitters of different wavelengths canbe used in the same or different optical links to make sure that theoptical connections are maintained in different weather and visibilityconditions. In one embodiment there are two different optical links tothe same direction, having different optics. One optical link for theconventional 1550 nm communication laser or the like, and anotheroptical link for the quantum cascade laser QCL that has a considerablylonger wavelength.

It should be noted that any features, phases or parts of the method 20can be freely permuted and combined with embodiments 10 and/or 30 inaccordance with the invention.

FIG. 3 shows an embodiment of the network using the inventive basestations deployed in a city as a block diagram. The buildings 320, 330,340, 350 each have the base stations of the invention on their roofs.The building 310 hosts an access point to the optical fibre network,and/or to the wireline communication network. In some embodiments it isan office building of the operator of the network of base stations (BS),for example the Central Office (CO) could reside in the building 310 insome embodiments.

The dashed lines in FIG. 3 present optical light beams, typicallynon-visible laser beams, that relay data optically through free space,which is air in this case. It is preferable to have line of sightconnections to multiple base stations and/or optical transceivers ratherthan to just one. This is because the operator can configure the networkto use a routing algorithm where if one line of sight connection fails,the data can be routed to the destination via an alternative route.Failure of one link can be due to optical transmitter failure, birdblocking the beam, or pointing misalignment due to movement of the basestation and/or beam expander focus and/or pointing, and preferably thenetwork is arranged to automatically detect these failures or a risk ofthese failures, so that correcting and/or pre-emptively correcting workcan be begun by e.g. system engineer of the operator running thenetwork. In some embodiments the signal strength of at least one opticallink is measured and sent to a network administration computer, forexample at/in the exchange and/or Central Office of the networkoperator.

By providing a wide spectral dynamic range at each laser link and manyalternative optical link topologies between two points, the probabilityof the signal having an eventual path between two points is increasedtowards certainty, even when some optical link might malfunction at someor all wavelengths.

The optical receiver in the optical transceiver and/or the base stationcomprises typically some photon collector, such as a parabolic mirror,antenna, dish antenna, and/or a large lens. Especially very longwavelength optical photons, such as QCL emitted photons, can in someembodiments be received more expediently with a photon receiver that isa reflector and/or an antenna or a similar photon collector. I.e. itcollects the incoming photons based on their wave like properties,rather than particle like properties. Typically the photon collector isarranged to focus and/or direct the collected photons to a photodiode.

Prior to optical fibre transmission, it is preferable to adapt the wholesignal to fibre transmission. In one embodiment this is simply adaptingthe different wavelengths used in free space communication to fibrecommunication. A free space SONET signal at a SONET wavelength can besent directly to the fibre with or without amplification in someembodiments. However, a SONET modulation compliant signal received witha QCL at for example 70,000 nm or some other different wavelength wouldpreferably need to be adapted to the SONET wavelength, which is about1550 nm in the IR.

In one preferred embodiment the inventive base stations are usedespecially by a new competing telecommunication operator that is tryingto enter a new market and win customers from existing operators. In someembodiments, the network is arranged to automatically directunregistered or unknown subscriber terminals to a webpage where they canregister as customers to the network. For example, if the competingoperator knows that broadband connections have been sold to a particularoffice building for 30 Euros/month, he can take a base station of theinvention to the roof of that office building and arrange it to show awebpage to users that log into the network, where the users of thesubscriber terminals can register as clients for only 20 Euros/month.When the users in the office building next log their subscriberterminals to the network of the competing operator they may simply signon as customers with their credit cards, or postal addresses forbilling, or the like. When the customers realise that the cells of theinventive base station are small enough to allow broadband over thewireless connection, they may well decide to abandon their existingfixed line contracts with their current original operators.

The invention is very cost efficient, as a broadband network can becreated by a very small team of system engineers, an access point tooptical core network, and a website+ client data centre accepting andmanaging payments and/or customer subscriptions.

It should be noted that any features, phases or parts of the method 30can be freely permuted and combined with embodiments 10 and/or 20 inaccordance with the invention.

It should be noted that all embodiments of the invention can be used notonly in duplex communication as described in the aforementioned, butalso in broadcast communication, such as TV and/or radio.

The invention has been explained above with reference to theaforementioned embodiments and several commercial and industrialadvantages have been demonstrated. The methods and arrangements of theinvention allow great synergistic advantages that go beyond the sum ofits parts. Using a FSO (free space optics) solution individuallyrelieves the network operator from the need to build optical cables tothe base station, but wire infrastructure would still need to be built,i.e. power cords. Similarly using the solar cell for a network basestation relieves the operator from making sure grid electricity isavailable, but again an optical fibre would need to be built. Theinvention allows the system engineer merely to only requestauthorisation from the tenants to place the base station on the roof.There is no need to consult the tenants for permissions to conductinfrastructural changes to the building itself, such as providing apower cord to the roof, or allowing for optical fibre wiring to the roofor into the rooms of the building. The inventor has calculated that thissaving should exceed more than 5000 Euros/building, which is thestandard quoted rate that large telecommunications companies cite as thecost of connecting a central Helsinki building to optical broadband, ina situation where the operator has an optical fibre nearby and trafficis not intervened with by digging up streets. Needless to say,infrastructure work outside the building is far more costly, and cancost millions of Euros even for connections shorter than a kilometre ifthe connection needs to be built in a high cost urban environment whereall disruptions to traffic etc. and other hindrances to the actual fibreor wire building work add to the cost.

Furthermore, the inventive base station is very cheap to manufacture inlarge quantities and numbers. Therefore the inventive base station hasthe added advantage that the cell size served by the base station can bemade very small. This allows for the introduction of quite small verybroadband radio cells, covering e.g. only the building, a particularfloor, section and/or room of a building. These small very highbandwidth radio cells have the advantage that they can be used tosubstitute an optical fibre connection to a residential or office unitall together. The invention therefore allows for example for all 18flats in an apartment building to enjoy 1/18 part of the bandwidth ofthe whole antenna array at worst (everybody using), but might deliverthe whole width of the radio/microwave band to the optical core networkfor one user (only one user accessing the network via the base station).Quite clearly this allows for video conferencing and other broadbandapplications to everybody at far more competitive commercial rates thanpeople are used to today.

The invention has been explained above with reference to theaforementioned embodiments. However, it is clear that the invention isnot only restricted to these embodiments, but comprises all possibleembodiments within the spirit and scope of the inventive thought and thefollowing patent claims.

REFERENCES

-   EP 1 476 968 B1, Mikko Kalervo Vaananen.-   EP 2261996, Mikko Kalervo Vaananen.-   EP 2226852, Mikko Kalervo Vaananen.-   EP 08735694.5, Mikko Kalervo Vaananen.-   EP 08803499.6, Mikko Kalervo Vaananen.-   WO 2006/044519, Peter Healey at al.

1. A base station (200), arranged to provide radio and/or microwavecommunication network access to at least one subscriber terminal (250,251) via at least one radio and/or microwave transmitter and/orreceiver, characterised in that, said base station comprises at leastone laser and/or photodiode data communication transmitter and/orreceiver (220, 221) arranged to transmit and/or receive photons throughfree space, said base station comprises at least one solar cell (240)which is flexible and shaped on the surface of the base station.
 2. Abase station (200) as claimed in claim 1, characterised in that, saidfree space laser and/or photodiode data communication transmitter and/orreceiver (220, 221) is realised with a photodiode laser and/or a quantumcascade laser, and/or is arranged to radiate directional photons in thevisible to 100,000 nm wavelength range or in the visible to 1 mmwavelength range.
 3. A base station (200) as claimed in claim 1,characterised in that, the said base station is arranged to receive atleast one free space laser and/or photodiode signal from another firstbase station and/or optical transceiver and transmit said received freespace laser and/or photodiode signal to a second base station and/oroptical transceiver through free space.
 4. A base station (200) asclaimed in claim 1, characterised in that, said free space laser and/orphotodiode data communication transmitter and/or receiver link (220,221) is arranged as a backhaul connection, arranged to simultaneouslycommunicate a plurality of signals exchanged with the said base stationand a plurality of subscriber terminals to one or more destinationswithin the communication network beyond the said free space laser and/orphotodiode communication link (220, 221) via the optical core networkand/or other communication network.
 5. A base station (200) as claimedin claim 1, characterised in that, at least one solar cell (240) isarranged to power said base station and/or store energy to a batterythat is arranged to power the base station.
 6. A base station (200) asclaimed in claim 1, characterised in that, said base station does nothave an electric socket for an external power cord and/or does not havean optical communication socket for an optical fibre connection.
 7. Abase station (200) as claimed in claim 1, characterised in that, saidsolar cell (240) is on the top face of the said base station and atleast one said free space laser and/or photodiode data communicationtransmitter and/or receiver (220, 221) is arranged to the side of thesaid base station, and/or at least one movable waveguide is arranged topoint the said at least one free space laser and/or photodiode datacommunication transmitter and/or receiver (220, 221) to the line ofsight direction of another base station and/or optical transceiver.
 8. Abase station (200) as claimed in claim 3, characterised in that, thesaid incoming free space laser and/or photodiode signal from saidanother first base station and/or optical transceiver is arranged to bereceived and amplified and sent to said another second base stationand/or optical transceiver through free space and/or, the said incomingfree space laser and/or photodiode signal from said another first basestation and/or optical transceiver is arranged to be received with afirst free space laser and/or photodiode data communication receiver(221) and sent with a second free space laser and/or photodiode datacommunication transmitter (220) or the same first free space laserand/or photodiode data communication transmitter and/or receiver (221)or both said transmitter and/or receivers (220, 221) to said anothersecond base station and/or optical transceiver through free space.
 9. Amethod of providing communication network access by operating at leastone base station (200) offering communication network access to aplurality of subscriber terminals (250, 251) via a radio and/ormicrowave connection, comprising the following steps: powering said atleast one base station with at least one solar cell) which is flexibleand shaped on the surface of the base station, in the same location asthe base station (120), connecting said base station to a communicationnetwork with at least one laser and/or photodiode data communicationlink through free space (110, 220, 221).
 10. A communication method asclaimed in claim 9, characterised in that, said free space laser and/orphotodiode data communication link (220, 221) is realised with aphotodiode laser and/or a quantum cascade laser, and/or said link (220,221) radiates directional photons in the visible to 100,000 nmwavelength range or in the visible to 1 mm wavelength range.
 11. Acommunication method as claimed in claim 9, characterised in that, thesaid base station receives at least one free space laser and/orphotodiode data communication signal from another first base stationand/or optical transceiver and transmits said received free space laserand/or photodiode data communication signal to a second base stationand/or optical transceiver through free space.
 12. A communicationmethod as claimed in claim 9, characterised in that, said free spacelaser and/or photodiode data communication link (220, 221) is a backhaulconnection, communicating simultaneously a plurality of signalsexchanged with the said base station (200) and a plurality of subscriberterminals (250, 251) to destinations within the communication networkbeyond the said free space laser and/or photodiode data communicationlink (220, 221) via the optical core network and/or other communicationnetwork.
 13. A communication method as claimed in claim 9, characterisedin that, at least one solar cell (240) is arranged to power said basestation (200) and/or store energy to a battery that is arranged to powerthe base station.
 14. A communication method as claimed in claim 9,characterised in that, said base station (200) does not have an electricsocket for an external power cord and/or does not have an opticalcommunication socket for an optical fibre connection.
 15. Acommunication method as claimed in claim 9, characterised in that, saidsolar cell (240) is on the top face of the said base station and atleast one said free space laser and/or photodiode data communicationlink (220, 221) is arranged to the side of the said base station, and/orat least one movable waveguide points the said at least one free spacelaser and/or photodiode data communication link (220, 221) to the lineof sight direction of another base station and/or optical transceiver.16. A communication method as claimed in claim 11, characterised inthat, the said incoming free space laser and/or photodiode datacommunication signal from said another first base station and/or opticaltransceiver is received and amplified and sent to said another secondbase station and/or optical transceiver through free space and/or, thesaid incoming free space laser and/or photodiode data communicationsignal from said another first base station and/or optical transceiveris received with a first free space laser and/or photodiode datacommunication link (221) and sent with a second free space laser and/orphotodiode data communication link (220) or the same first free spacelaser and/or photodiode data communication link (221) or both said links(220, 221) to said another second base station and/or opticaltransceiver through free space.